Friday, August 29, 2014

The Long Life of "Tropical" Cyclone Cristobal

Living a long life typically requires hitting the genetic jackpot, living in a relatively safe and healthy environment, taking care of yourself, and then perhaps just being plain lucky.  Swiss mountain guide Ulrich Inderbinen provides such an example.  He climbed the Materhorn 390 times, summited it a final time when he was 90, climbed 13,000 foot peaks in his 90s, worked until he was 95, and passed away this summer at 103.  Not too shabby.

Although not as far out there on the longevity limb as Ulrich Inderbinen, "Tropical" cyclone Cristobal, which moved poleward off the west east coast of North America this week, lived a pretty good life, benefiting from a caterpillar-to-butterfly-like metamorphosis from a tropical cyclone into a midlatitude cyclone as it moved into the North Atlantic.  

At the beginning of the loop below, Cristobal is barely a glint in his parent's eye and just a weak cluster of thunderstorms associated with a tropical easterly wave between Africa and the Lesser Antilles, islands that form the eastern edge of the Caribbean Sea.  He moves eastward and eventually experiences a quick birth and adolescence, growing into Hurricane Cristobal near the Bahamas.

The poleward movement of a hurricane into the cool waters of the higher latitudes often results in cyclone death, but Cristobal pulled off the necessary metamorphosis to extend his life, transitioning into an extratropical cyclone off the coast of the northeast United States and southeast Canada.  Such a transition requires a favorable large-scale environment, and Cristobal was fortunate to find himself in that environment as he crested the hill of middle age.  

Reborn as an extratropical cyclone, Cristobal is enjoying a productive maturity and is expected to survive until he reaches Iceland (see lower panel below).  

That's a lifetime from easterly wave through tropical cyclone to extratropical cyclone that spans nearly 2 weeks and almost 60ยบ of latitude, and a remarkable example of one type of tropical–extratropical interaction that occurs during late summer and fall in the Northern Hemisphere.  


  1. I think you meant east coast of North America... I spent far too long looking for it off the west coast...

    1. Egad. Can't tell my left from my right again. Thanks for the correction. Fixed.